[RFC PATCH v1 06/17] hw/riscv/virt: measure the device tree of a CoVE guest

[Baolong Duan <blduan@linux.alibaba.com>]

The device tree is the last piece of guest state that has to be part of
the initial measurement of a TEE VM.  The ROM blob holding it is only
written to guest memory when the machine is reset, which is too late, so
copy it into RAM and measure it right after its address is known.

Signed-off-by: Baolong Duan <blduan@linux.alibaba.com>
---
 hw/riscv/virt.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
index a76587d362..c15d8859ce 100644
--- a/hw/riscv/virt.c
+++ b/hw/riscv/virt.c
@@ -1277,6 +1277,24 @@ static void virt_machine_done(Notifier *notifier, void *data)
                                            machine, &boot_info);
     riscv_load_fdt(fdt_load_addr, machine->fdt);
 
+    /*
+     * The device tree is part of the initial measurement of a TVM. The ROM
+     * blobs holding it are not written to guest memory before the machine is
+     * reset, so copy it into RAM now to be able to measure it.
+     */
+    if (s->cove_vm) {
+        void *ram_base = memory_region_get_ram_ptr(machine->ram);
+        hwaddr fdt_offset = fdt_load_addr - s->memmap[VIRT_DRAM].base;
+        void *fdt_host;
+
+        memcpy((char *)ram_base + fdt_offset, machine->fdt, s->fdt_size);
+
+        fdt_host = kvm_gpa_to_userspace_addr(kvm_state, fdt_load_addr);
+        kvm_riscv_cove_measure_region((uint64_t)(uintptr_t)fdt_host,
+                                      fdt_load_addr,
+                                      ROUND_UP(s->fdt_size, 4 * KiB));
+    }
+
     /* load the reset vector */
     riscv_setup_rom_reset_vec(machine, &s->soc[0], start_addr,
                               s->memmap[VIRT_MROM].base,
-- 
2.34.1